Question

In a two digit number, the digit at tens place is 7 and the sum of the digits is 8 times the digit at unit place. Then the number is

• A. 71
• B. 17
• C. 70
• D. 78

Answer 1

Answer: (A)

The correct option is B 71
In the two digit number, let the digit in the units place is $x$ and the digit in the tens place is $7$.
$\therefore$ The number is $10\left(7\right)+x=70+x$
Sum of digits $=8$ times the digit in the units place.
$\therefore$ Sum of both the digits $=8\times$ digit at units place
$\therefore 7+x=8\times x$
$\therefore 7=7x$
$\therefore x=1$
Now, substituting $x=1$ in required number $70+x$, we get
$70+x=70+1=71$